This converter turns grams into milligrams instantly, using the exact factor 1 gram = 1000 milligrams. Type any number and the result updates as you go — nothing is sent to a server, so the arithmetic happens entirely in your browser.
One thousandth of a kilogram — the workhorse unit of cooking and postage. One thousandth of a gram, the standard unit for medication doses and nutrients.
Because the relationship is a simple proportion, one multiplication does the whole job. The table further down gives pre-computed values for the amounts people look up most often, and the result panel also reports the reverse conversion so you can check the figure both ways.
The formula
grams- The amount you are converting, measured in grams
1000- The exact number of milligrams in one gram
milligrams- The converted result
How it works, step by step
- Enter the number of grams you want to convert.
- The value is multiplied by 1000, the exact conversion factor.
- The result is displayed in milligrams, rounded for readability.
- The unrounded value and the reverse conversion appear underneath so you can verify it.
Worked examples
Converting 5 grams
Multiply 5 by 1000. That gives 5,000 milligrams. A quick sanity check: one gram is larger than one milligram, so the number should get bigger — and it does.
Converting 72 grams
72 × 1000 = 72,000 milligrams. Working backwards, 72,000 ÷ 1000 returns 72 grams, which confirms the factor is applied the right way round.
How to read your score
Frequently asked questions
How many milligrams are in one gram?
Exactly 1000. Every conversion on this page is that single number multiplied by your input, so the result carries no rounding error beyond what is shown.
What is the formula to convert grams to milligrams?
Milligrams = grams × 1000. To reverse it, divide instead: grams = milligrams ÷ 1000, which is the same as multiplying by 0.001.
Is the gram bigger than the milligram?
Yes. One gram equals 1000 milligrams, so it is the larger unit.
Why does my answer differ slightly from other grams to mg converters?
Most differences come from rounding the factor too early. This tool keeps full double precision through the calculation and only rounds at the final display step, and it also shows the unrounded value so you can see exactly where any difference appears.
What is a gram?
One thousandth of a kilogram — the workhorse unit of cooking and postage.
What is a milligram?
One thousandth of a gram, the standard unit for medication doses and nutrients.
Grams to milligrams reference table
| Grams | Milligrams |
|---|---|
| 0.5 g | 500 mg |
| 1 g | 1,000 mg |
| 2 g | 2,000 mg |
| 3 g | 3,000 mg |
| 5 g | 5,000 mg |
| 10 g | 10,000 mg |
| 15 g | 15,000 mg |
| 20 g | 20,000 mg |
| 25 g | 25,000 mg |
| 50 g | 50,000 mg |
| 75 g | 75,000 mg |
| 100 g | 100,000 mg |
| 250 g | 250,000 mg |
| 500 g | 500,000 mg |
| 1000 g | 1,000,000 mg |
Exact factor: 1 gram = 1000 milligrams. Values rounded for display.